Mapping a multiplexed zoo of mRNA expression.

Area of Science:

• Molecular Biology
• Developmental Biology
• Genomics

Background:

• In situ hybridization is crucial for mapping mRNA expression in biological specimens.
• Multiplexed mRNA analysis is vital for understanding gene regulation but is often complex.
• Existing methods for multiplexed in situ hybridization are cumbersome in many model organisms.

Purpose of the Study:

• To develop and demonstrate a versatile method for multiplexed in situ mRNA detection.
• To overcome the limitations of current techniques in terms of experimental complexity and organismal scope.
• To provide a tool for high-resolution spatial transcriptomics across diverse biological systems.

Main Methods:

• Utilized programmable in situ amplifiers based on the hybridization chain reaction (HCR) mechanism.
• Applied multiplexed in situ HCR across a wide range of model organisms, including bacteria, nematodes, fruit flies, sea urchins, zebrafish, chickens, and mice.
• Tested the method on formalin-fixed paraffin-embedded human tissue sections.

Main Results:

• Demonstrated successful multiplexed in situ HCR in bacteria, whole-mount embryos (nematode, fruit fly, sea urchin, zebrafish, chicken, mouse), and human tissue sections.
• Showcased the ability of in situ HCR to achieve deep sample penetration, high contrast, and subcellular resolution.
• Validated the independence of experimental timeline from the number of target mRNAs analyzed.

Conclusions:

• Multiplexed in situ HCR offers a simplified and scalable approach for mapping multiple mRNA targets simultaneously.
• The technique provides high-quality imaging across diverse biological specimens and experimental settings.
• In situ HCR is a powerful and broadly applicable tool for studying complex gene expression patterns in biological research.